Breakthrough in nuclear fusion: what do the new findings mean for the future of energy?


A color enhanced image of the interior of a NIF preamplifier support structure. Photo: Damien Jemison / US NIF / DoE

  • There are two possible ways to achieve nuclear fusion: magnetic confinement and inertial confinement.
  • On August 8, the US National Ignition Facility achieved historic energy production of 1.3 megajoules using the inertial approach.
  • While this new breakthrough is exciting, it should be borne in mind that fusion will be a source of energy for the second half of the century – at the earliest.

Lawrence Livermore National Laboratory announced a major breakthrough in nuclear fusion, using powerful lasers to produce 1.3 megajoules of energy – about 3% of the energy contained in 1 kg of crude oil.

Nuclear fusion has long been viewed as the energy of the future – an “infinite” source of energy that does not rely on the need to burn carbon. But after decades of research, it has yet to deliver on its exciting promise.

How close does this new breakthrough bring us to the desired results? Here’s a quick overview to put this new scientific breakthrough into perspective.

What is nuclear fusion?

There are two ways to use nuclear energy: fission, which is used in modern nuclear power plants, and fusion.

In fission, heavy uranium atoms are broken down into smaller atoms to release energy. Nuclear fusion is the reverse process: light atoms are transformed into heavier atoms to release energy, the same process that occurs in the plasma nucleus of the Sun.

A fusion reactor boosts power: the triggered reaction must produce more energy than is needed to heat the fuel plasma for energy production to occur – this is called the ignition. No one has managed to do it yet. The current record was set in 1997 by the Joint European Torus in the UK, where 16 MW of power was generated by magnetic fusion, but it took 23 MW to trigger it.

Inside the fusion chamber of Tokamak DIII-D, San Diego. Photo: Rswilcox / Flickr, CC BY-SA

There are two possible ways to achieve nuclear fusion: magnetic confinement, which uses strong magnets to confine the plasma for very long periods of time, and inertial confinement, which uses very powerful and short laser pulses to compress the fuel and trigger. the fusion reaction.

Historically, magnetic fusion has been favored because the technology necessary for inertial fusion, in particular lasers, was not available. Inertial fusion also requires much higher gains to compensate for the energy consumed by lasers.

Inertial containment

The two largest inertial projects are the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in the United States and the MegaJoule Laser in France, whose applications are mainly military and financed by defense programs. Both facilities simulate nuclear explosions for research purposes, although the NIF also conducts energy research.

The NIF uses 192 laser beams that produce a total of 1.9 megajoules of energy over a period of nanoseconds to trigger the fusion reaction. The fuel is placed inside a metal capsule a few millimeters in diameter, which, when heated by lasers, emits x-rays which heat and compress the fuel.

It is this process that, on August 8, 2021, reached the historic energy production of 1.3 megajoule, the highest value ever recorded by the inertial approach: that is, the closest to ignition.

The overall gain of 0.7 is equivalent to the record reached by the JET in 1997 using magnetic confinement, but in this case, the fuel absorbed 0.25 megajoules of energy and generated 1.3 megajoules: thus the fusion generated much of the heat required for the reaction, approaching the ignition point.

However, a reactor will have to achieve much higher gains (more than 100) to be economically attractive.

Magnetic containment

The magnetic confinement approach promises better development prospects and is therefore the preferred route for energy production to date.

The vast majority of research focuses on tokamaks, fusion reactors invented in the USSR in the 1960s, where the plasma is confined by a strong magnetic field.

ITER, a demonstration reactor under construction in the south of France involving 35 countries, uses the tokamak configuration. It will be the largest fusion reactor in the world, and aims to demonstrate a gain of 10 – the plasma will be heated by 50 MW of power and is expected to generate 500 MW. The first plasma is now officially expected by the end of 2025, with a fusion demonstration expected in the late 2030s.

The UK recently launched the spherical tokamak for power generation (STAGE) which aims to develop a reactor that connects to the energy grid in the 2040s. China is also pursuing a ambitious program produce isotopes of tritium and electricity in the 2040s. Finally, Europe plans to open another tokamak demonstrator, DEMO, in the 2050s.

Another configuration called the stellarator, like that of Germany Wendelstein-7X, shows very good results. Although the performance of a stellarator is lower than what a tokamak can achieve, its inherent stability and promising recent results make it a serious alternative.

The future of fusion

Meanwhile, private nuclear fusion projects have exploded in recent years. Most of them envision a fusion reaction in the next ten to twenty years and together have attracted $ 2 billion in funding get ahead of the traditional development sector.

Two different scenarios of nuclear fusion deployment, compared to wind, solar and nuclear fission. Image Title: G. De Temmerman, D. Chuard, J.-B. Rudelle for Zenon Research, author provided

If these initiatives use other innovative technologies to achieve fusion and could thus very well deliver operational reactors quickly, the deployment of a fleet of reactors around the world will necessarily take time.

If development follows this accelerated path, nuclear fusion could account for around 1% of global energy demand by 2060.

So while this new breakthrough is exciting, it should be borne in mind that fusion will be a source of energy for the second half of the century – at the earliest.The conversation

Greg De Temmerman, Associate researcher at Mines ParisTech-PSL; Managing Director of Zenon Research, Mines ParisTech.

This article was first published by The conversation and has been republished here under a Creative Commons license.

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